There have hitherto been a network conference system (refer to Patent document 1) which accumulates conference data about a network conference and regenerates the conference data at a variable speed and also an electronic conference system (refer to Patent document 2) enabling users participating afterward to catch up with a discussion proceeding in real time by providing past messages to these participants in a way that narrows down or compresses time intervals of the past messages and thus reproduces the messages.
Moreover, an AV (Audio Visual) system (refer to Patent document 3) exists, which enables a viewer to retrieve an interrupted position and continuously view the program when moving away from a TV in the middle of viewing the program and returning thereto.
Furthermore, there is an operator support system (refer to Patent document 4) which records a call (conversation) of an operator and attaches a tag associated with details of the call to a record of the call.    [Patent document 1] Japanese Patent Laid-Open Publication No. 2005-244522    [Patent document 2] Japanese Patent Laid-Open Publication No. H11-205314    [Patent document 3] Japanese Patent Laid-Open Publication No. 2006-135532    [Patent document 4] International Publication Pamphlet WO 2004/023772